Interfitting lock for containers



May 4, 1954 G. E. WAUDA 677,493

INTERFITTING LOCK FOR CONTAINERS Filed March 14., 1949 2 Sheets-Sheet l l f Jzv'cizzz'w ,/f 666:76 Wanda' May 4, 1954 G. E. WAUDA 2,677,493

INTERFITTINGl LOCK FOR CONTAINERS Filed March 14, 1949 2 Sheets-Sheet 2 9 m 'MA/2 Patented May 4, 1954 INTERFITTING LOCK FOR CONTAINERS George E. Wanda,

Neenah, Wis., assignor to Marathon Corporation, Rothschild, Wis., a corporation of Wisconsin Application March 14, 1949, Serial No. 81,256

1 Claim.

This invention relates to a collapsible container or box and more particularly to an improved locking means for locking together wall portions of such containers or boxes.

The principal object of this invention is to provide a container which can be formed from a blank preferably from relatively stiff material such as paper board by automatic packaging equipment. It is a further object to provide locking connections between portions of said blank which require no adhesive when forming the blank into a container. It is still a further object to provide a locking connection which is so designed so as to have a high resistance against opening even when relatively thin flexible materials and particularly laminated materials are used and it is yet another object to provide a locking connection which is suiciently iiexible to insure rapid locking by mechanical means without loss of wall strength in the :finished container.

Other objects and advantages of my invention will appear from the following description, including the drawings forming a part thereof, and wherein like numerals are used for like parts in each of the gures, of trays incorporating my improved locking means.

Figure 1 is a plan view of a container or tray of my invention in blank or collapsed form.

Figure 2 is a front perspective view showing one end of my container partially set up.

Figure 3 is a fragmentary plan perspective view showing in more detail the relative position of the parts of my locking device in Figure 2.

Figure 4 is similar to Figure 3 with the carton fully set up.

Figure 5 is a fragmentary plan view showing the relative position of the parts of my locking device in set up position.

Figure 6 is a front perspective of my completed container.

Figure 7 is a fragmentary plan view of a tray in the blank or knocked down form having a modified locking device of my invention.

Figure 8 is similar to Figure 2 showing my modified locking device.

Figure 9 is similar to Figure 3 showing my modified locking device.

Figure 10 is similar to Figure 4 showing my modified locking device.

Figure 11 is a partial front perspective view of the nished container of Figure 7.

Figure 12 is a fragmentary plan view of the tray in Figure 1 in the blank showing still another modification of the locking device.

LlO

The blank of Figure 1 is suitably cut and scored in the conventional manner to provide a bottom wall I to which is hingedly connected along score lines 2 and 3 side walls 4 and 5 and along score lines 6 and 'I side or end walls 8 and S. To the end wall 8 hingedly connected by score lines Ill and I I forming the edges of end wall 8 are flaps I2 and I3. Similarly hingedly connected to end wall 9 by score lines I4 and I5 are flaps IE and I'I.

In setting up a container from the blank in Figure 1 the walls 4, 5, 8 and 9 are all folded upwardly to a position at right angles to the bottom wall l and the aps I2, I3, I6 and I1 are then folded at right angles to walls 8 and 9 so as to overlie portions of walls 4 and 5 all as is conventional in setting up collapsible types of cartons or containers. To maintain the relative parts of the container in the position described locking means are provided between adjacent side walls and where it is desired not to use adhesives such locking means usually provide a tongue on one member which engages a slit on the other member.

The improved locking means of my container, which I shall describe with respect to one corner thereof since each of the corners is identical, comprises a slit 2G which is cut in the side wall 4 and a cooperating tongue 2l which is integral with and formed from ap I6. In the modification of my container in Figure 1 the slit 2o comprises a straight section 22 which extends upwardly from the score line 2 and inwardly from the edge 23 of the side wall 4 for a distance substantially mid-way up the side wall and a second straight slit 24 joining slit 22 which extends further upwardly in the side wall 4 and preferably is cut at an angle of substantially to score line 2, that is, to the bottom of the container. Slit 24 terminates short of the top edge 25 of side wall 4. The proximity of the end of the slit 24 and edge 25 is determined solely by the strength required in the lock since the material in the side wall therebetween determines the strength of the lock.

The tongue 2l may be considered as being in two parts. One part is the slit engaging portion 25, which preferably but not necessarily extends beyond the front edge of flap I6, having a top edge 27 and a bottom edge 28. Edge 28 is a continuation of the bottom edge of ap I5. The other part of the tongue is referred to as the hinge portion 29 and is formed in the lower portion of nap i6 by a slit 3l] cut back into the body of the ap from the front edge 3|. Preferably line i4, itsv actual length being determined byv the degree of flexibility desired in the tongue and the strength requirements of the tongue de pending upon the material from. whichthe carton is made. The strength of the tongue is of course determined by the amount of material between the end of the slit 30 and the bottom. edgel 2t.

of the iap. It should be noted that the edge 28 is a straight edge formed by a. slit which is in substantial alinement with score line 1.

Referring now to Figures 2, 3, 4 and 5, after the slit 2U has been partially opened by mechanin cal. devices in. the= automatic. packaging machine in which my container. istobe set up, the tongue 2 t. is inserted intoYthe-slit. In.the position shown in Figures-2 and3 it willbe. noted that thedistortion in the slit due tothe. insertion. of the tongue setsup forces due to-the inherent ren siliency ofl the. material. For example, in- Figure 3. the area: adjacent-the slit as indicated by 35.has been=extended outwardly and hence tends to exert a force inwardly on the tongue 2i. The portion. of. the wall. 4v as indicated.v in @E has been distorted inwardlyI by the flap i5 and hence ttendstocausethe-ilap to be bowed outwardly. The distortion between the flap and the side wall is. due to, the fact4 that score line Ul andscore. line 2 are substantially in alinement. As.the-tongue. is further. inserted in the slit 2t to the point where the edge 21A of. the tongue is below. or in alineme-ntwith. the upper portion 24. of. slit Zllfthepressure of` the wall portion 35.

is greater. than. the resistence of the iiexible tongue and hence,. the. tongue is snapped inwardly toeffectengagement ofthe edge21. with the locking portion of the slit 24. This snapping inof` the tongue is` effectively. accentuated first by the increased. flexibility of the-.tongue due to its.

great effective length and by the` fact that the portion. 3S of the flap. l,. which lies above the tongue, that is above the. slit 38, is still being urged. outwardly. by the distortion of. the. wall portion 35. In prior, devices thatI, have known where the tongue. is merely an extension of a flap, thereis not the combination of forces present which I have foundfmakemy. locking means more effective in automatic. machinery. Whenl in theseprior devicesY there isan. attempt to increase. the flexibility of. the tongue. by extending them further beyond the edge of the flap to which they are connected there. is. notr only a loss of. strength at. the junction between the flap andv the side` wall because of the lack of supportwhich the ap would contribute and does contribute in my. locking device, that isportion 32, but thereis not the degree of opposing forces present which create a snapping action in the engagementof thetongue with the lock.

Figure. 5 more clearly. showsthat the effective length. of. the tongue in my locking device extends from a point 31 which is determined by the end of slit 3Q to the front edge of the tongue and that the.. portion 39, of thelflap It which is above the slit Siloverlies the side walllt and hence contributes strength. tov the carton at a point Where it. would. otherwise.` be. weakened by the presenceofthe slit,2ll.

It was previously pointed out the upper portion 24 of slit 20 and the top edge 21 of my locking tongue 2l form an approximately equal angle substantially e. g. 45 with the bottom of the container and hence when the tongue is in locking position these two edges coincide. My lock is greatly strengthened by this fact since it does not dependonits luckingfstrength for single point contact. In some applications, however; I prefer to have the relative angle of my tongue and slit, and the flexibility of my tongue, such that the lockY takes.. place in the crotch formed by the tongue andthe flap. This is particularly desirable'. whenusing laminated board stock. My lock is' further. strengthened by the fact that when in locking position the bottom edge 28 of. the. locking flap substantially rests on the bottom wall' I' of my container and hence supports the;side.or end wall 9 against any inward pressure which would otherwise only be resisted by the abutment of` the. sidewall 4.- with the end ofv side wall 5. It is--seenthat this strut action of the flap- I5` is. only made possible by theV extension of slit 2B to the. scoreline 2. Previous attempts of. which I- am aware te obtain strut action. by cutting. outa portion of. the bottom edge ofA theflaptofprovide a front foot which wouldV passV through. a. slit: whichwould not extend to. the score line but which would rest on the bottom. wall. ofl a. container` have not. come into. use becausev of` the practically impossibilit' of manufacture and=l inherent. weakness whenadaptedto smallv sized containers.

In4 the embodiment,- of.' my invention` of. Figure 1 through. 1.1. I. have shown another form of lecking slit. which. has .certain advantages depending upon the typev of mechanical.. apparatus used to effect thecpening. thereof. In. all other. respects the parts arethe same, asthosefinigure l and like numerals have: been, used for iilre parts throughout.

The. slit.4 infthe container in-Figure '1v in side wall 4 comprises.asingle'straight slit extending. upwardly from` thev score. line 2. and outwardly from;thef edge 2.3, of. the. side wall` preferably atv an. angle of. substantially 45 toscore line 2 or the bottom wallr I. of the container. The slit 4l. terminates below. the top edge 25 of the sidev wall. 4- and. the distance. below is determinedinthesame manner` as .was eseribezl for the container ofY Figuresl through. 6. Substantially midrway along. the. lengthof slit 4i isa second slit.42 whiclr intercepts. slit lll. at substantially right angles. The slit 42 serves to weaken the area. of. the.. side wall which is distorted inwardly by the action oi the. tongue so. as to facilitate. entrance. ot the tongue into the. slit. It. will. be. seen in Figures 8` and 9, however, that the portion 4.3.. of the sidewall below the. slit is. unbrokenv and. hence will. exert a pressure inwardly on the tongue to eectuate the locking action. previously described. It will readily b e seen also that by forming the tongue from the flap I6. through. slit, 3&1' I. have made available portion 39.. ofA flap. I6.. for overlying a greater portion of the area of. side. wall. 42 which has been weakenedby.- slit. 42; Where mechanie cal equipment is so designedlthat theslit t0. can be openedsufliciently to permit the insertion of the tongue without including. in. slit. iii the ad ditional. slit. 42,` this. slit may be. dispensed with without losing the. advantages. of my improved locking means. such. as the line locking action at the substantially. same angleto the. bottom.

wall I, the strut action obtained by having slit 4I extend from the score line 2, and the increased exibility of my tongue without the loss of strength due to forming the tongue from flap I 6 by slit 3l).

Another modification in the structure of the locking tongue which is particularly useful when using thick board is shown in Figure 12. This modified tongue structure is shown in relation to the tray of Figure 1 though it will be readily understood that tray of Figure 7 could also be so modified. In this modication I provide a hinge for the tongue in the form of a vertical score line 50 extending from the end of slit 39 down to the bottom edge 28. Obviously each of the tongues could be so modied in either tray shown.

It is appreciated that though I have shown various modifications of my improved locking means in connection with a tray type of container i various of its advantages will be obtained when locking Walls together in other forms of collapsible containers which conventionally use tongue and slit locking devices, therefore, no limitations are intended by the above description except such as are contained in the following claim.

I claim:

In a carton a bottom Wall, at least two adjacent side Walls at substantial right angles to each other, a locking ap connected to one of the contiguous edges of one of said side walls and adapted to overlie a portion of said other side wall and having a front edge opposite its connection to said one side Wall, a slit out in said other side wall extending from the base of said wall upwardly and angularly away from the edge of said wall to a point below the upper edge thereof at least the upper portion of said slit being disposed at about 45 angle to the base of said wall and a locking tongue integral with and formed from said Iiap and extending forwardly from the bottom portion oi the front edge of said ap, said tongue having a slit engaging portion extending beyond the front edge or. the upper portion of said flap and having an upper edge disposed at an angle of about 45 to the base of said flap and a hinge portion partially cut out from the lower portion of said ap by a slit extending rearwardly from the front edge of said flap back into the body of said flap, said slit being a straight line continuation of the top edge of said slit engaging portion.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,079,583 Seegmiller Nov. 25, 1913 1,652,251 Oliver Dec. 13, 1927 2,124,699 Harrington July 28, 1938 2,218,509 Goodyear Oct. 22, 1940 2,447,563 Buttery Aug. 24, 1948 2,475,279 Dunnng July 5, 1949 2,488,704 Buttery Nov. 22, 1949 2,536,384 Meller Jan. 2, 1951 2,550,582 Meller Apr. 24, 1951 2,578,878 Buttery Dec. 18, 1951 2,580,181 Meller Dec. 25, 1951 

